Southern Visitors

Courtesy of a wonderful couple in Yorkville, IL:

Black-bellied Whistling-Ducks (Dendrocygna autumnalis), 

Kendall Co, IL 5/26/2014

 These beauties are Black-bellied Whistling-Ducks (Dendrocygna autumnalis). They are native to the southern US, from Louisiana, Texas, and Arizona south to South America. When the Spaniards arrived in Texas, they were apparently quite common there, but they had almost disappeared by the early 1900's. (1) However, habitat alteration in the 1940's and 1950's enabled them to rebound, and by 1964 they were well established in 4 counties in southernmost Texas.

Today, they are a breeding species in much of eastern Texas and Louisiana, and apparently quite regular near Memphis, Tennessee. There are records scattered the length of Illinois -- the birds shown above have been hanging around a housing development just southwest of Chicago for a week now. But if you look at the 1980's, you won't find a single Illinois record on e-bird. (To some extent that may be due to a lack of data as well as a lack of birds.) This is one species that is expanding dramatically as the weather warms.

This has been a constant theme for some time now, actually. Blue-gray Gnatcatchers are now an expected breeding species across all of Illinois and most of Wisconsin, whereas in the 1970's, records are almost non-existent in both NE Illinois and Wisconsin. (Again, limited coverage is part of that, but I've talked to birders from that era that took special trips to Indiana Dunes just to see the breeding gnatcatchers there. Today, it would be a rare forest preserve that didn't have them nesting.) Red-bellied Woodpeckers, Northern Cardinals, Northern Mockingbirds, Blue Grosbeaks, and so on, have all been shifting their ranges northwards over the late 20'th and early 21st centuries.

Now, species ranges can shift for all sorts of reasons. There's been speculation that the winter finch invasions that used to be part of a normal Chicago winter have been sadly reduced because of an increase in people feeding birds in Wisconsin and Michigan, for instance. But when most of the species that you see shifting are all going the same direction, there's something going on that needs to be addressed, and climate change appears to be the only hypothesis going here.

There is one thing neat about this topic -- for many species, we simply can't tell what they're doing. Even if we go out and start looking hard, right now, we wouldn't be able to say that ranges are shifting for quite a few years now. But with birds, we have a nice long history of observations we can fall back on, thanks to the efforts of amateur birders all over the world.

(1) Bolen, E. G., McDaniel, B., & Cottam, C. (1964). Natural history of the black-bellied tree duck (Dendrocygna autumnalis) in southern Texas. The Southwestern Naturalist, 78-88.